Factors associated with adverse reactions to cocaine among a sample of long-term, high-dose users in São Paulo, Brazil.

This cross-sectional survey investigates the frequency of adverse cocaine reactions and associated factors among regular cocaine misusers. A sample of 332 cocaine misusers from a range of treatment and nontreatment settings in São Paulo, Brazil, were interviewed using a questionnaire that includes the Severity of Dependence Scale (SDS), the General Health Questionnaire (GHQ-28), the CAGE, and an eight-item questionnaire investigating the frequency of specific adverse cocaine reactions. The most commonly described reactions were hot flushes (84%), uncontrollable shaking (76%), and feeling ill (75%). The most severe symptoms and least common were convulsions or fits (18%) and passing out (21%). Frequency of adverse reactions to cocaine was positively associated with out-of-treatment status, severity of cocaine dependence, ever having injected cocaine, using tranquilisers with cocaine, and GHQ score. Adverse reactions to cocaine are common among regular cocaine users. Some of the adverse effects, especially those on the heart and central nervous system, are potentially fatal. Preventive strategies should be developed to reduce the risk of adverse cocaine reactions. The findings are discussed in relation to the type of interventions that might be developed and lines of future research.